Math Equations

Question 1

Lost volume

Answer 1

(PIP - PEEP) x TCF

Question 2

TCF (tubing compliance factor)

Answer 2

Expired volume / PIP

Question 3

I:E ratio

Answer 3

(TCT - Ti) / Ti

Question 4

Minute ventilation (MV)

Answer 4

RR x Vt (in L)

Question 5

Flow

Answer 5

MV x sum of I + E / 60
(So that it is put in L/sec)

Question 6

TCT (total cycle time)

Answer 6

60 / RR

Question 7

I-time (inspiratory time, Ti)

Answer 7

Vt (in L) / Flow (in L/sec)

Question 8

Static compliance

Answer 8

Exhaled Vt / Plat - PEEP

Question 9

Dynamic compliance

Answer 9

Exhaled Vt / PIP - PEEP

Question 10

Airway resistance (RAW)

Answer 10

PIP- PLAT / Flowrate (in L/sec)

Question 11

Ideal body weight (IBW)

Answer 11

Male 106 + 6 (ht. in inches-60)
Female 105 + 5 (ht. in inches-60)

Question 12

What is the normal range for cstatic, cdynamic and RAW?

Answer 12

cstatic- 60-100 (more accurate)
cdynamic- 35-50
RAW- <10

Question 13

Conditions that cause static compliance

Answer 13

ARDS, atelectasis, tension pneumothorax, obesity, retained secretions

Question 14

Conditions that cause dynamic compliance

Answer 14

Bronchospasm, kinking of ET tube, airway obstruction

Question 15

Increase in airway resistance will ______ the PIP, but the Plat will ________.

Answer 15

Increase, stay the same

Question 16

Does mild or uncomplicated V/Q mismatch respond well to O2 therapy?

Answer 16

YES

Question 17

Intrapulmonary shunting causes what type of hypoxemia?

Answer 17

Refractory

Question 18

What is oxygenation failure?

Answer 18

Severe hypoxemia (PaO2 < 40 mmHg) despite high FiO2 (50-100%)